Wow, six years of high school?? I only have four....
I think you should absolutely try. And if your book is good enough, then good luck getting it published!! ^^
But then again, I'm only in high school, so I don't know much about getting books published. I think you should go for it anyways...
Because they haven't gained much experience yet, so their writing isn't as good as it could be. I hope to get something published in the future, but I doubt I will be under 21. However, if I was, then great. But it seems highly improbable. This isn't much of a surprise to me.